Hello. I am mono, my husband is poly and has had a gf for over a year. I would highly suggest your wife join the boards and read everything she can. There are a few blogs on here written by monos who share their experiences, ups and downs, breakthroughs and more. You would also benefit by reading blogs from a mono point of view. However, it's one thing to talk about it - it's a completely different thing to actually experience it.
The key is patience and communication!
Best of luck!